Information disclosure in Composer
CVE-2026-45793
Composer is a dependency Manager for the PHP language. Prior to 1.10.28, 2.2.28, and 2.9.8, Composer\IO\BaseIO::loadConfiguration() validates GitHub OAuth tokens with the regex ^[.A-Za-z0-9_]+$ and interpolates rejected tokens into an UnexpectedValueException; GitHub Actions GITHUB_TOKEN values using the ghs_<id>_<base64url-JWT> format can contain -, fail validation, and be disclosed to stderr or CI logs. This issue is fixed in versions 1.10.28, 2.2.28, and 2.9.8.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.010 (63.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- Composer — versions >= 1.0, < 1.10.28, >= 2.0.0, < 2.2.28, >= 2.3.0, < 2.9.8
Weakness classification (CWE)
References
- github.com/composer/composer/security/advisories/GHSA-f9f8-rm49-7jv2
- github.com/composer/composer/pull/12853
- github.com/composer/composer/pull/12855
- github.com/composer/composer/commit/3f5e7f9fbfa541137d6d1d5643ec3b718e9d5039
- github.com/composer/composer/commit/65e6390c49f1a11cd8b660d81822086db51fe2d1
- github.com/composer/composer/commit/e66c8fdb7ff5409bd2f358c5f194038e49e93714
- github.com/composer/composer/releases/tag/1.10.28
- github.com/composer/composer/releases/tag/2.2.28
- github.com/composer/composer/releases/tag/2.9.8
Frequently asked questions
- What is CVE-2026-45793?
- CVE-2026-45793 is a high-severity vulnerability in Composer, classified under Information Disclosure. CVSS score: 7.5/10. Published 2026-07-15.
- How severe is CVE-2026-45793?
- High severity. CVSS v3 base score is 7.5 out of 10.